It is often desirable to use headphones when listing to music and other audio material. For example, users commonly use headphones when listening to music that is being played back from a portable music player. Over-the-ear headphones are sometimes used, particularly in environments in which size is not a major concern. When a compact size is desired, users often use in-ear headphones (sometimes termed “earbuds”). Earbuds are popular because they form a seal in the ear that helps to reduce ambient noise while retaining the compact size of other in-ear designs.
When earbuds are used by different people, there are variances in frequency response at the Drum Reference Point (DRP). These variances may be caused by different amounts of occlusion that the headphone creates when it is placed in the user's ear, which may be the result of the following factors: 1) inconsistency in the positioning of the headphone in the user's ear; 2) different sizes/shapes of the user's ears; and 3) the headphone moving in the user's ear due to stress, shaking, jogging, etc. Accordingly, it would be beneficial to compensate for these variances and provide a consistent response at the DRP.